Method and apparatus for die casting by pressure injection

ABSTRACT

A method and apparatus for pressure die casting in which the frame carrying the gated die is counterbalanced over the injection nozzle for movement between a lowered seated position and a raised unseated position, and floated initially to seat the gate on the nozzle. Certain of the interfitting die parts are moved and releasably locked by applying, by pivotal leverage through the die frame, a force acting in the direction of closing movement of the die, preferably by wedge means acting parallel to that direction. The sprue in the die is sheared by moving the gated die part laterally, and a subsequent lateral movement of the gated die part may introduce pressurized fluid into the die cavity to blow the sprue from the gate.

United States Patent m1 3,701,377 Fisher Oct. 31, 1972 [54] METHOD ANDAPPARATUS FOR DIE 1,952,201 3/1934 Flammang et al. ..l64/309 CASTING BYPRESSURE INJECTION 1,999,961 4/1935 Daeson et ..l64/l l9 2,108,0802/1938 Schultz, Jr. et al. ..164/ll3 [72] gff gt fg gfi" Pete 3,450,1906/1969 Mittermaieret al ..l64/309 [73] Assignee: Fisher Gauge Limited,Peter- Primary Examiner-R. Spencer Annear borough, Ontario, CanadaAttorney-Westell & Hanley [22] Filed: Sept. 29, 1970 [57] ABSTRACT [21]Appl' 76483 A method and apparatus for pressure die casting in which theframe carrying. the gated! die is counter- [30] Foreign ApplicationPriority Data balanced over the injection nozzle for movement between alowered seated position and a raised un- 1969 Great Bmam "50011/69seated position, and floated initially to seat the gate on the nozzle.Certain of the interfitting die parts are [52] US. Cl. 11664173133, 1166123299, ll6641/l33379, moved and releasably lacked by applying" bypivotal [51] I t Cl B22d,27/14 Bzzd 33/04 leverage through the dieframe, a force acting in the [58] d 119 5 303 306 direction of closingmovement of the die, preferably 0 can 2 by wedge means acting parallelto that direction. The sprue in the die is sheared by moving the gateddie part laterally, and a subsequent lateral movement of [56] Referencescued the gated die part may introduce pressurized fluid into UNITEDSTATES PATENTS the die cavity to blow the sprue from the gate.

1,555,284 9/1925 Hoey ..l64/264 22 Claims, 10 Drawing FiguresPATENTEDnBIaI m2 sum 1 or a NVENT OR WILLIAM F. FISHER PME'N'TEDnm 31I972 SHEET 2 0F 8 [\VENT OR WILLIAM F. FISHER @m I W PATENTEUUEISI m2 3.701 377 sum 3 or 8 INVENTOR.

WILLIAM F. FISHER P'ATENTED nm 3 1 1912 SHEET 4 0f 8 FIG. 4

NVEN TOR WILLIAM F. FISHER PATENTED 0m 3 1 I972 SHEET 5 BF 8 FIG. 5

INVENTOR.

WILLIAM F. FISHER PAIENTEDuma 1 I972 3. 701; 377

SHEEI 7 [1F 8 FIG, 7

INVENTOR WILLIAM F. FISHER METHOD AND APPARATUS FOR DIE CASTING BYPRESSURE INJECTION This invention relates to die casting.

Die casting includes the encapsulation of jet engine compressor andturbine blades which consists of surrounding each blade with a block ofmetal, the surfaces of the block having a precise relationship with theairfoil to permit correct orientation for subsequent machining of theroot and tip of the blade. A current method of encapsulation employs alow melting point, non-shrinking alloy which is poured into a mould ordie having the blade positioned in the die. This is slow and alsoexpensive both with regard to production and with regard to the alloyitself.

The present invention overcomes these disadvantages by providing amethod and apparatus for pressure die casting which increases the speedof encapsulation and uses a low cost alloy having a shrinkage factor andhigher melting point. This is accomplished by counter-balancing theheavy die frame (on which the die is mounted) required for encapsulationproduction whereby accurate seating of the gate on the injection nozzleis obtained.

Another problem in pressure die casting is the force required to ensurethat the die is properly closed against the high internal pressure ofthe injected metal. Devices presently in use employ a heavy hydrauliccylinder or a toggle mechanism assembly to close and lock the moving dieparts.

In another aspect the present invention overcomes this disadvantage byproviding an improved method for closing and releasably locking a diepart in a pressure die casting operation, and an apparatus foraccomplishing this purpose which is lighter but simple to manufacture,operate and maintain. This is achieved by applying, through pivotableleverage, a force in a direction parallel but opposite to the reactiveforce on the die when closed, such force acting through the die frame.

Die casting apparatus normally employs a core punch or similar device tocut and remove the sprue or plug from the gate after casting. Thepresent invention in another aspect provides a simple method and meansfor sprue severance and removal by using a laterally movable die plateto shear the sprue, the slidable plate being used to expose an aperturein the die cavity and inject lubricating mist and/or air, underpressure, into the cavity which acts to eject the sprue remaining in thegate from the previous casting if the sprue has not already fallen out.

It will be appreciated that the various. aspects of the invention areapplicable to die casting operations other than encapsulation.

Example embodiments of the invention are shown in the accompanyingdrawings, in which:

FIG. 1 is a view in perspective of a die casting apparatus;

FIG. 2 is a perspective view, partly broken away, of the movablesupporting mechanism for the apparatus of FIG. 1;

FIG. 3 is a view in elevation of the supporting mechanism of FIG. 2 inits closed position over the injection nozzle of the apparatus;

FIG. 4 is a view similar to FIG. 3 showing the supporting mechanism inits open position away from the injection nozzle;

FIG. 5 is a view in perspective of a die closing mechanism used in theapparatus of] FIG. 1;

FIG. 6 is a cross-sectional view in elevation of the die closingapparatus of FIG. 5;

FIG. 7 is a view taken along the line 7-7 of FIG. 6;

FIG. 8 is a plan view of a die open at the top and with a turbine bladelocated in the die cavity for encapsulation;

FIG. 9 is a cross-section taken generally along the line 9-9 of FIG. 8,with the die fully closed, and

FIG. 10 is a perspective view of the locating pins and actuatingmechanism shown in FIG. 8.

The apparatus of FIG. 1 consists of a die frame 10 mounted on a movablesupporting mechanism 11 which is in turn mounted on a fixed base 12. Apot 13 for molten metal is mounted in base 12 together with an injectionpump 14, and fixed injection nozzle 15 projects upwardly from pot 13below frame 10, in a manner known in the art, for instance as shown inapplicants US. Pat. No. 3,256,572 issued June 21, 1966.

Frame 10 carries a pair of die parts 16 and 17 each fixed on a dieclosing mechanism 18 mounted on the frame at right angles one to theother, a transversely movable lower die plate 19 mounted on a cross-armof the frame, and a fixed die part 21 mounted on the frame inconjunction with an ejection mechanism 22.

As seen in FIG. 2 of the drawings, supporting mechanism 11 comprises aU-shaped yoke or bar 25 located about a pillar 26 of base 2 and havingeach arm 27 pivotally mounted on the underside of a top plate 28 of thebase (see FIGS. 3 and 4) by means of a connecting arm 29 pinned freelyat each end to the arm and top plate respectively. Cross-arm 31 of bar25 is pivotally mounted through a channel link 32 on trunnions 33 fixedto pillar 26 of base 12. Cross-arm 31 of bar 25 is also pivotallyconnected, on each side of trunnions 33,

to a lower plate 34 of base 12 by a fluid cylinder and piston assembly35. Finally, arms 27 of bar 25 each carry a T-shaped pillar 36 whichproject through slots 37 in top plate 28 of base 12 and to whichcross-arm 20 of die frame 12 is attached. The face of upper end plate 38of pillar 36 is recessed to provide a cavity 39, connected with fluidpressure means (preferably air) to float cross-arm 20 of frame 10. Endplate 38 also carries apertures 39a to receive bolts for anchoring frame10 after it has been oriented on supporting mechanism 11.

FIGS. 3 and 4 of the drawings shows lower die plate 19 having a gate 40and a nozzle seat 41, and also show with a drive assembly 42 for movingdie plate 19 onto and away from nozzle 15. Drive assembly 42 consists ofa drive arm 43 pivoted at one end to channel link 32 and at the otherend eccentrically to a drive wheel 44 which is keyed to a pinion 45engaging a rack 46 carrying a piston 46a actuable by a hydrauliccylinder 47 to I move in either direction. A limit switch 48 is actuableby a pin 49 fixed on drive wheel 44. A threaded stop pin 50 bearsagainst drive arm 43 in its lower portion as shown in H6. 3, when nozzle15 is in seat 41 of die plate 19. Drive wheel 44, pinion 45, rack 46 andcylinders 47 are all mounted on a frame 51 which is slidable in a keyway5'2 and adjustable vertically in the keyway by a threaded shaft 53actuable by a handwheel 54.

In FIGS. 5, 6 and 7 of the drawings die closing apparatus 18 is shownwhich consists of a cylindrical shaft v 60 mounted in blocks 61 and 61aon die frame 10 for longitudinal movement. Block 61 carries a pair ofopposed guide keys 62 which extend along shaft 60, and a pair of latchmembers 63 are rotatably mounted each on a pin 63a, in recesses 62a ofguide keys 62. Mounted adjacent one end of shaft 60 are an inner ring 64and an outer ring 65, the outer ring abutting the inner ring. Bothrings64 and 65 have a pair of notches 66 to accommodate keys 62 whileouter ring 65 has an an additional notch 67 engageable by a finger 68extending laterally from a piston-actuated shaft 69 (see FIG. 7). A pairof wedges 70 mounted on the pistons of a pair of hydraulic cylinders 71are adapted to move between block 61 and latches 63. Each wedge 70carries an adjustable stop nut 72 and a spring loaded ball 73 which isalso adjustable on the wedge and serves to give clearance for outer ring65.

As seen in FIG. 6, shaft 60 carries a piston ring 75 which moves in ahydraulic cylinder 76 mounted between blocks 61 and 62. Within shaft 60is a concentric intermediate prestressed shaft 77 which carries at itsouter end a flanged collar 78 carrying outer ring 65 concentricallyrotatable on the collar. An opposed pair of studs 79 key inner ring 64to shaft 60 and are held in position by a threaded nut 80 bearingagainst collar 78. A hydraulic cylinder 81 is threaded onto nut 80 andactuates a rod 82 concentrically mounted within shaft 77. A plate 83held by nut 80 interacts with a limit switch 84 on block 61. Fixed onthe end of shaft 77 adjacent block 62 is a die holding plate 85. It willbe noted from FIGS. and 6 that tie bolts 130 secure blocks 61 and 61a toframe 10. The axis of each pair of bolts 130 preferably intersect, orlie near, the axis of adjacent pin 63a on which latch 63 freely pivots.

All die parts 16, 17, 19 and 21 are water cooled. As seen in FIG. 1,lower die plate 19 is movable by a pair of hydraulic cylinders 90 havingtheir pistons 91 engaging the die plate. In addition to gate 40, dieplate 19 has an aperture 92 which is located beneath one wall of diepart 21 when the die plate is in a position of rest and is connectedwith a flexible conduit through a passageway 93 for pressure injectionof a lubricating mist.

FIGS. 8 to of the drawings shows the structure of the die assembly. FIG.8 shows die parts 16 and 21 closed together with a blade 100 located indie cavity 101, root 102 of the blade being at the top (dotted in FIG. 8for clarity). Core pieces 103 (not shown in FIG. 9 for clarity) projectfrom die parts 16 and 21 into the cavity to reduce the volume of thecavity. A locating pin 104 (FIG. 9 only) and ejection pins 105 (FIG. 8only) also project into die cavity 101, and also as root support pin106. I

Fixed locating pins 110 project into die cavity 101 from die part 21while resilient locating pins 111 project into the die cavity from diepart 16. Pins 110 and 111 are arranged for holding blades of differentcrosssections. As seen in FIGS. 8 and 10, pins 111 are mounted onbarrels 112 slidable in cavities 113 in die part 16 and urged forward bycompression springs 114. A bar 115 engaging notches 1 16 in barrels 112is linked by a pin 115a slidable in a slot 117 in a lever bar 118 whichis pivoted on a pin 1 19. Rod 82 (see FIG. 6) terminates in a linkagearrangement 120 which, when rod 82 is moved in the direction of arrow121 by cylinder 81 clamps barrels 112 against the walls of cavities 1 13and locks pins 111 in position against blade 100. When rod 82 isreleased and lever 118 is moved laterally in the direction of arrow 122,pins 111 are pulled, against the action of springs 114 away from blade100. Altemately, compressive spring pressure may be exerted on lever 118instead of on cylinders 112, allowing the pressure on pins 1 11 to beequalized.

Before initiating the cyclical operation of the apparatus of FIGS. 1 to4, horizontal die plate 19 is first located on nozzle 15 by movingfloating cross-arm 20 on upper plates 38 of pillars 36 while supportingmechanism 11 is in its lowered position as seen in FIG. 3 of thedrawings. Cross-arm 20 is then bolted to upper plates 38 and supportingmechanism 11 is moved to its raised position as seen in FIG. 4 of thedrawings.

In the cyclical operation of the apparatus of FIGS. 1 to 4, horizontaldie part 16 is closed against fixed die part 21, whereupon a turbineblade 100 to be encapsulated is inserted into the die cavity, in themanner described with respect to FIGS. 8 to 10, and vertical die part 17is closed against die parts 16 and 21. The operation of the die closingapparatus will be described subsequently with respect to FIGS. 5 to 7 ofthe drawings. After die parts 16 and 17 have been moved to close thedie, die plate 19 is then slid forward by cylinders to expose aperture92 and inject lubricating mist into the die cavity, which also serves toeject the sprue or slug, of the previous casting, for gate 40 if it hasnot already fallen into pot 13. Die plate 19 is then returned bycylinders 90 to its original position.

In the next operational step, die plate 19 is lowered to seat nozzle 15in gate 40. This is done by actuating piston 46a integral with rack 46and movable in cylinders 47, to rotate pinion 45 and drive wheel 44 in aclockwise direction which causes arm 43 to rotate channel link 32 andmove bar 25 forwardly as seen in FIG. 3. The rotation of drive wheel 44is stopped by pin 50 just after the center line of arm 43 passes thecenter of rotation of the drive wheel to lock die plate 19 againstnozzle 15. Altemately the rotation of drive wheel 44 may be stopped byhaving the end of rack 46 strike the end of either cylinder 47.Cylinders 35 provide sufficient hydraulic pressure to give die frame 10a negative weight so that drive assembly 42 must pull bar 25 downwardly.The amount of pressure of die plate 19 on nozzle 15 can be adjusted byhandwheel 54 which slides frame 51 in keyway 52, after which lockingbolts 510 can be tightened.

Limit switch 48 initiates he next operational step, in which moltenmetal is injected by pump 14 from pot 13 through nozzle 15 and gate 40into the die cavity, in known manner. When the molten metal has beenallowed to stand in the die cavity long enough to solidify, frame 10 ismoved by drive assembly 42 to lift die plate 19 away from nozzle 15 andto one side of the nozzle. After a further time to allow the casting tocool, the lock releases on the pins and die parts 16'and 17 are releasedand retract, the casting being held in position by the sprue or plug.Die plate 19 is then moved horizontally by pistons 91 to sever the plugin gate 40 from the casting. The position of frame 10 enables the plugto fall from die plate 19 into pot 13 clear of nozzle 15. If the plugdoes not drop from gate 40 it will be ejected in the next operationalcycle when lubricating mist is injected under pressure into the closeddie through aperture 92 as previously described. Ejection device 22 isthen actuated to push the casting from fixed die part 21 in knownmanner.

In the operation of the die closing apparatus 18 of FIGS. 5, 6 and 7,piston 75 is actuated within cylinder 76 to move shaft 77 forward (tothe left in flGS. 5 and 6), rings 64 and 65 moving along keys 62 untilouter ring 65 is located in annular recesses 62a of the keys while innerring 64 remains keyed, as seen in FIGS. 6 and 7. This actuates limitswitch 84 which in turn actuates shaft 69 to cause finger 68 to rotateouter ring 65 whereby notches 66 are moved out of alignment with keys62. Hydraulic cylinders 71 are then actuated to move wedges 70 againstlatches 63, causing the latches to bear against outer ring 65 with acompressive force which locks die part 16 (or 17) tightly against thecomplementary parts of the die.

It should be noted that die closing mechanism 18 may be adapted torotate its associated die part for sprue severance. This is done bywidening notch 66 of inner ring 64 and fixing outer ring 65 to he innerring so that both rings are rotatable as a single unit. The die part ismounted on one end of an inner slide (equivalent to shaft 77) and thetwo rings 64 and 65 are mounted on the other end, whereby the thrust istransmitted through the inner slide; the outer slide (equivalent topiston 75) acting merely to move the assembly back and forth byhydraulic means.

I claim:

1. A method of pressure die casting employing an injection apparatushaving a nozzle and a die frame carrying a gated die seatable on thenozzle, comprising the steps of: i

supporting the die frame above the nozzle on movable means andcounterbalancing the supporting means between a lowered position and araised position;

floating the die frame on the movable supporting means by fluid pressureto precisely align and seat the gate of the die on the nozzle when thesupporting means is in the lowered position, and anchoring the die frameon the supporting means when the gate is seated on the nozzle; and

lowering and raising the movable supporting means to seat and unseat thedie on the nozzle in a cyclical casting operation.

2. A method as claimed in claim 1 in which the supporting means iscounterbalanced by fluid pressure urging the supporting means about apivot into the raised position.

3. A method as claimed in claim 1 in which the supporting means is movedboth axially and laterally with respect to the nozzle. v

4. A method as claimed in claim 1 in which the supporting means isreleasably locked in the lowered positron.

5. Apparatus for pressure die casting using an injection nozzle andmeans for the controlled feeding of molten metal through the nozzle,comprising:

a die frame having die parts mountable thereon including a die gate;

means supporting the die frame, said supporting means beingcounterbalanced and movable between a lowered position and a raisedposition;

means to float the die frame on the supporting means whereby the diegate is precisely aligned and seated on the injection nozzle when thesupporting means is in the lowered position, and means to anchor the dieframe on the supporting means when the gate is seated on the nozzle; and

means to lower and to raise the counterbalanced supporting means wherebythe die gate is cyclically seated and unseated on the injection nozzle.

6. Apparatus as claimed in claim 5 in which the supporting meansincludes a yoke pivotally mounted adjacent one end on a fixed base andsupported adjacent the other end by fluid piston means adapted to urgethe yoke towards the raised position.

7. Apparatus as claimed in claim 5 in which the lowering and raisingmeans is adapted to move the die gate both axially and laterally withrespect to the nozzle.

8. Apparatus as claimed in claim 5 in which the supporting means isadapted to be releasably locked in the lowered position.

9. Apparatus as claimed in claim 6 in which the raising and loweringmeans comprises link means pivotably interconnecting the base and thefree end of the yoke, and means to pivot the link means about the base.

10. Apparatus as claimed in claim 9 in which the pivoting meanscomprises a rack and pinion assembly,

a drive wheel keyed to the pinion, and a drive arm pivotably connectingthe drive wheel and the link means, and fluid pressure means adapted toactuate the pinion reciprocally.

11. Apparatus as claimed in claim 10 in which the pinion is adapted tomove the drive arm past dead center to abut stop means whereby thesupporting means is releasably locked in the lowered position.

12. In a pressure die casting operation employing a plurality of dieparts mounted on a die frame and interfitting to form a die cavity, amethod of releasably closing and locking at least one of said die partscomprising the steps of:

moving said one die part, in a direction opposite to the reactive forceon the die when closed and charged, to close the die;

applying, by pivotal leverage through the die frame when the die isclosed, a force acting on said one die part in the direction of closureof the die, said force acting through the die frame and sufficient towithstand the reactive force on the die part when the die is charged.

13. A method as claimed in claim 12 in which a said force is efiected bywedge action applied through the die frame in a direction parallel tosaid reactive force.

14. In pressure die casting apparatus, a device for moving and locking adie part to close a die mounted on a die frame, comprising:

means mounting the die part on the die frame;

means to move the die part mount, in a direction op-,

posite to the reactive force on the die part when closed and charged, toclose the die;

at least one latch member pivotably mounted on the die frame andengagable with the die part mount when the die is closed; and

means mounted on the die frame and actuable, when the die is closed, toengage: he latch member whereby the latch member bears against the diepart mount in the direction of closure thereof.

15. A device as claimed in claim 14 in which the means to engage thelatch member comprises wedge means actuated by hydraulic means fixed onthe die frame.

16. A device as claimed in claim 15 in which the wedge means is adaptedto move against the latch member in a direction parallel and opposite tosaid direction of closure.

17. A method of pressure die casting employing a plurality of die partsinterfitting to form a die cavity, one of said die parts carrying a diegate adapted to seat on an injection nozzle, comprising the steps of:

seating the die gate on the nozzle and injecting molten casting materialthrough the nozzle into the die cavity; allowing the molten material tosolidify and moving the die to unseat the die gate from the injectionnozzle;

moving laterally that die part carrying the die gate to shear the sprue,formed by solidification of the molten material in the die gate, fromthe casting in the die cavity;

separating the die parts to remove the casting from the die cavity,reclosing the die parts to re-form the die cavity, and

moving laterally that die part carrying the die gate to expose anaperture therein and introduce fluid under pressure into the die cavitywhereby the sheared sprue if retained in the die gate is ejectedtherefrom.

18. A method as claimed in claim 17 in which the pressurized fluid is alubricating mist.

19. A die for use in pressure casting, comprising:

a plurality of die parts interfitting to form a die cavione of said dieparts having a flat inner surface and being adapted to slide laterallyalong said surface, and said one die part carrying a gate therein forinjection of molten casting material into the die cavity, an aperture insaid one die part opening into said cavity, said aperture being adaptedto register with a duct connecting said die with a source of pressurizedfluid whereby, when said one die part is slid laterally a predetermineddistance along said surface and when said die cavity is empty, saidfluid is released under pressure into said cavity whereby a shearedsprue if retained in the gate is ejected therefrom.

20. A die as claimed in claim 19 in which the pressurized fluid is alubricating mist.

21. Apparatus as claimed in claim 5 in which the means to float the dieframe comprises at least one cavity located in the supporting means, thedie frame including a surface portion covering the cavity, and fluidpressure means connecting with the cavity whereby the die frame ismovable laterally on the sup porting means.

22. A device as claimed in claim 14 including a guide key fixed to thedie frame in the direction of closure of the die part mount and havingthe latch member coextensive therewith, first slotted means fixed on thedie part mount and engagable with the guide key to prevent lateralrotation of the mount, second slotted means rotatable on the die partmount, the second slotted means being engagable with the guide keyexcept when the mount is closed an laterally rotat ble when the mount isclose to provi e a bearing su ace for the latch member against themount.

1. A method of pressure die casting employing an injection apparatushaving a nozzle and a die frame carrying a gated die seatable on thenozzle, comprising the steps of: supporting the die frame above thenozzle on movable means and counterbalancing the supporting meansbetween a lowered position and a raised position; floating the die frameon the movable supporting means by fluid pressure to precisely align andseat the gate of the die on the nozzle when the supporting means is inthe lowered position, and anchoring the die frame on the supportingmeans when the gate is seated on the nozzle; and lowering and raisingthe movable supporting means to seat and unseat the die on the nozzle ina cyclical casting operation.
 2. A method as claimed in claim 1 in whichthe supporting means is counterbalanced by fluid pressure urging thesupporting means about a pivot into the raised position.
 3. A method asclaimed in claim 1 in which the supporting means is moved both axiallyand laterally with respect to the nozzle.
 4. A method as claimed inclaim 1 in which the supporting means is releasably locked in thelowered position.
 5. Apparatus for pressure die casting using aninjection nozzle and means for the controlled feeding of molten metalthrough the nozzle, comprising: a die frame having die parts mountablethereon including a die gate; means supporting the die frame, saidsupporting means being counterbalanced and movable between a loweredposition and a raised position; means to float the die frame on thesupporting means whereby the die gate is precisely aligned and seated onthe injection nozzle when the supporting means is in the loweredposition, and means to anchor the die frame on the supporting means whenthe gate is seated on the nozzle; and means to lower and to raise thecounterbalanced supporting means whereby the die gate is cyclicallyseated and unseated on the injection nozzle.
 6. Apparatus as claimed inclaim 5 in which the supporting means includes a yoke pivotally mountedadjacent one end on a fixed base and supported adjacent the other end byfluid piston means adapted to urge the yoke towards the raised position.7. Apparatus as claimed in claim 5 in which the lowering and raisingmeans is adapted to move the die gate both axially and laterally withrespect to the nozzle.
 8. Apparatus as claimed in claim 5 in which thesupporting means is adapted to be releasably locked in the loweredposition.
 9. Apparatus as claimed in claim 6 in which the raising andlowering means comprises link means pivotably interconnecting the baseand the free end of the yoke, and means to pivot the link means aboutthe base.
 10. Apparatus as claimed in claim 9 in which the pivotingmeans comprises a rack and pinion assembly, a drive wheel keyed to thepinion, and a drive arm pivotably connecting the drive wheel and thelink means, and fluid pressure means adapted to actuate the pinionreciprocally.
 11. Apparatus as claimed in claim 10 in which the pinionis adapted to move the drive arm past dead center to abut stop meanswhereby the supporting means is releasably locked in the loweredposition.
 12. In a pressure die casting operation employing a pluralityof die parts mounted on a die frame and interfitting to form a diecavity, a method of releasably closing and locking at least one of saiddie parts comprising the steps of: moving said one die part, in adirection opposite to the reactive force on the die when closed andcharGed, to close the die; applying, by pivotal leverage through the dieframe when the die is closed, a force acting on said one die part in thedirection of closure of the die, said force acting through the die frameand sufficient to withstand the reactive force on the die part when thedie is charged.
 13. A method as claimed in claim 12 in which a saidforce is effected by wedge action applied through the die frame in adirection parallel to said reactive force.
 14. In pressure die castingapparatus, a device for moving and locking a die part to close a diemounted on a die frame, comprising: means mounting the die part on thedie frame; means to move the die part mount, in a direction opposite tothe reactive force on the die part when closed and charged, to close thedie; at least one latch member pivotably mounted on the die frame andengagable with the die part mount when the die is closed; and meansmounted on the die frame and actuable, when the die is closed, to engagethe latch member whereby the latch member bears against the die partmount in the direction of closure thereof.
 15. A device as claimed inclaim 14 in which the means to engage the latch member comprises wedgemeans actuated by hydraulic means fixed on the die frame.
 16. A deviceas claimed in claim 15 in which the wedge means is adapted to moveagainst the latch member in a direction parallel and opposite to saiddirection of closure.
 17. A method of pressure die casting employing aplurality of die parts interfitting to form a die cavity, one of saiddie parts carrying a die gate adapted to seat on an injection nozzle,comprising the steps of: seating the die gate on the nozzle andinjecting molten casting material through the nozzle into the diecavity; allowing the molten material to solidify and moving the die tounseat the die gate from the injection nozzle; moving laterally that diepart carrying the die gate to shear the sprue, formed by solidificationof the molten material in the die gate, from the casting in the diecavity; separating the die parts to remove the casting from the diecavity, reclosing the die parts to re-form the die cavity, and movinglaterally that die part carrying the die gate to expose an aperturetherein and introduce fluid under pressure into the die cavity wherebythe sheared sprue if retained in the die gate is ejected therefrom. 18.A method as claimed in claim 17 in which the pressurized fluid is alubricating mist.
 19. A die for use in pressure casting, comprising: aplurality of die parts interfitting to form a die cavity; one of saiddie parts having a flat inner surface and being adapted to slidelaterally along said surface, and said one die part carrying a gatetherein for injection of molten casting material into the die cavity, anaperture in said one die part opening into said cavity, said aperturebeing adapted to register with a duct connecting said die with a sourceof pressurized fluid whereby, when said one die part is slid laterally apredetermined distance along said surface and when said die cavity isempty, said fluid is released under pressure into said cavity whereby asheared sprue if retained in the gate is ejected therefrom.
 20. A die asclaimed in claim 19 in which the pressurized fluid is a lubricatingmist.
 21. Apparatus as claimed in claim 5 in which the means to floatthe die frame comprises at least one cavity located in the supportingmeans, the die frame including a surface portion covering the cavity,and fluid pressure means connecting with the cavity whereby the dieframe is movable laterally on the supporting means.
 22. A device asclaimed in claim 14 including a guide key fixed to the die frame in thedirection of closure of the die part mount and having the latch membercoextensive therewith, first slotted means fixed on the die part mountand engagable with the guide key to prevent lateral rotation of themount, second slotted means rotatable on tHe die part mount, the secondslotted means being engagable with the guide key except when the mountis closed and laterally rotatable when the mount is closed to provide abearing surface for the latch member against the mount.